Outcome of Psychosis Better If Patients Stop Cannabis

MedicalResearch.com Interview with:
Dr Sagnik Bhattacharyya
Reader in Translational Neuroscience and Psychiatry
Institute of Psychiatry, Psychology & Neuroscience, KCL
Consultant Psychiatrist, Early Intervention Pathway
Director, Maudsley Early Intervention in Dual Diagnosis clinic
Psychosis Clinical Academic Group, South London & Maudsley NHS Foundation Trust
King’s Health Partners 

MedicalResearch.com: What is the background for this study? What are the main findings?

Dr. Bhattacharyya: Cannabis is the most commonly used illicit drug in the world and its use has been linked to the onset of psychotic disorders such as schizophrenia. Whilst a lot of research has investigated the association between cannabis use and the development of psychosis, there is less clarity regarding the consequences of continued cannabis use in those with an established psychotic disorder. We therefore pooled together all available evidence from studies that specifically looked at the effects of cannabis use on outcome following the onset of psychosis. Based on data from more than 16000 patients with a first episode or more established psychosis, our results show that continued cannabis use is consistently associated with poor outcome in the form of more relapses (as indexed by psychiatric hospitalisation), longer hospitalisations and increased positive symptoms. However, outcomes were not as bad if cannabis use was discontinued following the onset of psychosis.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Bhattacharyya: Outcome of psychosis is better, in particular the risk of relapse of psychosis and hospitalisation is lower, in those patients with psychosis who stop using cannabis after the onset of psychosis compared to those who continue to use the drug. It is therefore particularly important for clinicians to focus on helping those with an established psychotic disorder stop ongoing cannabis use.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Bhattacharyya: In this meta-analysis, we were able to examine only the effect of a relatively gross estimate of cannabis use on outcome in psychosis, because that is what has been reported in most published studies to date. As a result we were not able to examine whether outcomes may differ based on frequency of use or type of cannabis used or indeed whether some patients were more sensitive than others to the effects of cannabis. This is important as we know that getting everyone to completely stop using cannabis may be harder to achieve than getting some of them to use less often or switch to less potent forms of the drug. However, it is not clear on the basis of current evidence whether this may be associated with better outcome. Future studies need to focus on examining these aspects in order to allow clinicians offer more specific and personalized recommendations to their patients.

MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.


Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis

Published Online: DOI: http://dx.doi.org/10.1016/S2215-0366(15)00363-6

The Lancet Psychiatry , Volume 3 , Issue 3 , 215 – 225

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Dr Sagnik Bhattacharyya (2016). Outcome of Psychosis Better If Patients Stop Cannabis MedicalResearch.com

Last Updated on March 8, 2016 by Marie Benz MD FAAD